From 5d8d82d529597010bcd1ece30aec5b1a8d5ff905 Mon Sep 17 00:00:00 2001
From: Christian Pointner <equinox@spreadspace.org>
Date: Thu, 24 Aug 2023 23:50:56 +0200
Subject: add nftables prometheus exporter

---
 roles/monitoring/prometheus/exporter/meta/main.yml |  2 +
 .../prometheus/exporter/nftables/defaults/main.yml |  2 +
 .../prometheus/exporter/nftables/handlers/main.yml | 10 ++++
 .../prometheus/exporter/nftables/tasks/main.yml    | 55 ++++++++++++++++++++++
 .../exporter/nftables/templates/config.yml.j2      |  4 ++
 .../exporter/nftables/templates/service.j2         | 31 ++++++++++++
 .../prometheus/server/defaults/main/main.yml       |  1 +
 .../server/defaults/main/rules_nftables.yml        | 11 +++++
 8 files changed, 116 insertions(+)
 create mode 100644 roles/monitoring/prometheus/exporter/nftables/defaults/main.yml
 create mode 100644 roles/monitoring/prometheus/exporter/nftables/handlers/main.yml
 create mode 100644 roles/monitoring/prometheus/exporter/nftables/tasks/main.yml
 create mode 100644 roles/monitoring/prometheus/exporter/nftables/templates/config.yml.j2
 create mode 100644 roles/monitoring/prometheus/exporter/nftables/templates/service.j2
 create mode 100644 roles/monitoring/prometheus/server/defaults/main/rules_nftables.yml

diff --git a/roles/monitoring/prometheus/exporter/meta/main.yml b/roles/monitoring/prometheus/exporter/meta/main.yml
index 10a251f4..0b466ac9 100644
--- a/roles/monitoring/prometheus/exporter/meta/main.yml
+++ b/roles/monitoring/prometheus/exporter/meta/main.yml
@@ -25,4 +25,6 @@ dependencies:
     when: "'modbus' in (prometheus_exporters_default | union(prometheus_exporters_extra))"
   - role: monitoring/prometheus/exporter/chrony
     when: "'chrony' in (prometheus_exporters_default | union(prometheus_exporters_extra))"
+  - role: monitoring/prometheus/exporter/nftables
+    when: "'nftables' in (prometheus_exporters_default | union(prometheus_exporters_extra))"
   - role: monitoring/prometheus/exporter/register
diff --git a/roles/monitoring/prometheus/exporter/nftables/defaults/main.yml b/roles/monitoring/prometheus/exporter/nftables/defaults/main.yml
new file mode 100644
index 00000000..c4c42756
--- /dev/null
+++ b/roles/monitoring/prometheus/exporter/nftables/defaults/main.yml
@@ -0,0 +1,2 @@
+---
+# prometheus_exporter_nftables_version:
diff --git a/roles/monitoring/prometheus/exporter/nftables/handlers/main.yml b/roles/monitoring/prometheus/exporter/nftables/handlers/main.yml
new file mode 100644
index 00000000..a78363f8
--- /dev/null
+++ b/roles/monitoring/prometheus/exporter/nftables/handlers/main.yml
@@ -0,0 +1,10 @@
+---
+- name: restart prometheus-nftables-exporter
+  service:
+    name: prometheus-nftables-exporter
+    state: restarted
+
+- name: reload nginx
+  service:
+    name: nginx
+    state: reloaded
diff --git a/roles/monitoring/prometheus/exporter/nftables/tasks/main.yml b/roles/monitoring/prometheus/exporter/nftables/tasks/main.yml
new file mode 100644
index 00000000..47022026
--- /dev/null
+++ b/roles/monitoring/prometheus/exporter/nftables/tasks/main.yml
@@ -0,0 +1,55 @@
+---
+- name: generate apt pin file for exporter-nftables package
+  when: prometheus_exporter_nftables_version is defined
+  copy:
+    dest: "/etc/apt/preferences.d/prom-exporter-nftables.pref"
+    content: |
+      Package: prom-exporter-nftables
+      Pin: version {{ prometheus_exporter_nftables_version }}-1
+      Pin-Priority: 1001
+
+- name: remove apt pin file for exporter-nftables package
+  when: prometheus_exporter_nftables_version is not defined
+  file:
+    path: "/etc/apt/preferences.d/prom-exporter-nftables.pref"
+    state: absent
+
+- name: install apt packages
+  apt:
+    name: "prom-exporter-nftables{% if prometheus_exporter_nftables_version is defined %}={{ prometheus_exporter_nftables_version }}-1{% endif %}"
+    state: present
+    allow_downgrade: yes
+  notify: restart prometheus-nftables-exporter
+
+- name: create config directory
+  file:
+    path: /etc/prometheus/exporter/nftables
+    state: directory
+
+- name: generate configuration
+  template:
+    src: config.yml.j2
+    dest: /etc/prometheus/exporter/nftables/config.yml
+  notify: restart prometheus-nftables-exporter
+
+- name: generate systemd service unit
+  template:
+    src: service.j2
+    dest: /etc/systemd/system/prometheus-nftables-exporter.service
+  notify: restart prometheus-nftables-exporter
+
+- name: make sure prometheus-nftables-exporter is enabled and started
+  systemd:
+    name: prometheus-nftables-exporter.service
+    daemon_reload: yes
+    state: started
+    enabled: yes
+
+- name: register exporter
+  copy:
+    content: |
+      location = /nftables {
+          proxy_pass http://127.0.0.1:9630/metrics;
+      }
+    dest: /etc/prometheus/exporter/nftables.locations
+  notify: reload nginx
diff --git a/roles/monitoring/prometheus/exporter/nftables/templates/config.yml.j2 b/roles/monitoring/prometheus/exporter/nftables/templates/config.yml.j2
new file mode 100644
index 00000000..07c32bd1
--- /dev/null
+++ b/roles/monitoring/prometheus/exporter/nftables/templates/config.yml.j2
@@ -0,0 +1,4 @@
+# {{ ansible_managed }}
+
+nftables_exporter:
+  bind_to: "127.0.0.1:9630"
diff --git a/roles/monitoring/prometheus/exporter/nftables/templates/service.j2 b/roles/monitoring/prometheus/exporter/nftables/templates/service.j2
new file mode 100644
index 00000000..b22d9582
--- /dev/null
+++ b/roles/monitoring/prometheus/exporter/nftables/templates/service.j2
@@ -0,0 +1,31 @@
+[Unit]
+Description=Prometheus nftables exporter
+After=systemd-modules-load.service
+
+[Service]
+Restart=always
+User=prometheus-exporter
+ExecStart=/usr/bin/prometheus-nftables-exporter --config=/etc/prometheus/exporter/nftables/config.yml
+ExecReload=/bin/kill -HUP $MAINPID
+
+# systemd hardening-options
+AmbientCapabilities=CAP_NET_ADMIN
+CapabilityBoundingSet=CAP_NET_ADMIN
+DeviceAllow=/dev/null rw
+DevicePolicy=strict
+LockPersonality=true
+MemoryDenyWriteExecute=true
+NoNewPrivileges=true
+PrivateTmp=true
+ProtectControlGroups=true
+ProtectHome=true
+ProtectKernelModules=true
+ProtectKernelTunables=true
+ProtectSystem=strict
+RemoveIPC=true
+RestrictNamespaces=true
+RestrictRealtime=true
+SystemCallArchitectures=native
+
+[Install]
+WantedBy=multi-user.target
diff --git a/roles/monitoring/prometheus/server/defaults/main/main.yml b/roles/monitoring/prometheus/server/defaults/main/main.yml
index 1e0dcf32..7a9adde4 100644
--- a/roles/monitoring/prometheus/server/defaults/main/main.yml
+++ b/roles/monitoring/prometheus/server/defaults/main/main.yml
@@ -38,6 +38,7 @@ prometheus_server_rules:
   standalone-kubelet: "{{ prometheus_server_rules_standalone_kubelet + prometheus_server_rules_standalone_kubelet_extra }}"
   modbus: "{{ prometheus_server_rules_modbus + prometheus_server_rules_modbus_extra }}"
   modbus/probe: "{{ prometheus_server_rules_modbus__probe + prometheus_server_rules_modbus__probe_extra }}"
+  nftables: "{{ prometheus_server_rules_nftables + prometheus_server_rules_nftables_extra }}"
 
 # prometheus_server_alertmanager:
 #   url: "127.0.0.1:9093"
diff --git a/roles/monitoring/prometheus/server/defaults/main/rules_nftables.yml b/roles/monitoring/prometheus/server/defaults/main/rules_nftables.yml
new file mode 100644
index 00000000..8ce0b1c9
--- /dev/null
+++ b/roles/monitoring/prometheus/server/defaults/main/rules_nftables.yml
@@ -0,0 +1,11 @@
+---
+prometheus_server_rules_nftables_extra: []
+prometheus_server_rules_nftables:
+  - alert: NftablesFailedToReadRuleset
+    expr: nftables_up == 0
+    for: 2m
+    labels:
+      severity: warning
+    annotations:
+      summary: Unable to read nftables ruleset (instance {{ '{{' }} $labels.instance {{ '}}' }})
+      description: "The nftables collector failed to read the ruleset from the kernel.\n  VALUE = {{ '{{' }} $value {{ '}}' }}\n  LABELS = {{ '{{' }} $labels {{ '}}' }}"
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